so i just now did a test on my 10gallon tank with about 5 live plants one betta and a mystery snail. i thought this tank was done cycling as its been set up for over two months now and i havent had any problems with it. i noticed some growth on the filter and on the front glass. it only gets about 8-10 hours of sunlight a day. any advice would be nice. thanks

here is the growth on the filter, its also on some of the plants and the front glass of the tank, before we converted to a natural tank we did notice something like this growing on the decorations we had in the tank. i thought it was rust at first but when we removed the decoration it (the decor) dried off we couldnt see the "rust" anymore

I actually have that in 1 of my 10 tanks but my tests aren't off. It's my 16 gallon which is full of plants also. It's frustrating because I can't get anything online that explains it either. Only thing I suspect is the water company was doing work on the water lines 1 day before I changed that tanks water and I keep on feeling like this needs water hardness test but all I have is strip tests for that which I don't trust. IDK... anyone else have insight?

Brown algae looks like that and is hard to get cleaned up. Otos eat it but that is the only fish/snail i have seen that touches it. If it isn't that, then i have no idea but it will grow all over the tank, filter, plants until the bloom is over. Sometimes conditions in the water will make different kinds of algae bloom.